php-mock

autoload.php

<?php

// autoload.php
// php5.3 <=

spl_autoload_register(function($name) {
    require __DIR__."/lib/".$name.".php";
});

Sample.php

<?php
// lib/Sample.php
class Sample {
    static private $instance = null;

    private function __construct() {
    }

    static public function getInstance() {
        if (null === self::$instance) {
            self::$instance = new Sample();
        }

        return self::$instance;
    }

    public function hello() {
        return "Hello";
    }
}

test1.php

<?php

// test1.php

require __DIR__."/autoload.php";

// Mock class
class Sample {
    static private $instance = null;

    private function __construct() {
    }

    static public function getInstance() {
        if (null === self::$instance) {
            self::$instance = new Sample();
        }

        return self::$instance;
    }

    public function hello() {
        return "こんにちは";
    }
}

echo Sample::getInstance()->hello(); // こんにちは

test2.php

<?php

// test2.php

require "lib/Sample.php";

runkit_method_redefine("Sample", "hello", "", "return 'こんにちは';", RUNKIT_ACC_PUBLIC);

echo Sample::getInstance()->hello(); // こんにちは